1. Field of the Invention
The present invention relates to a liquid electrographic imaging system, and more particularly, to a transfer roller cleaning apparatus of a liquid electrographic imaging system which removes left-over developing solution and foreign materials stuck to the surface of a transfer roller which transfers a developed image formed on a photosensitive medium to paper.
2. Description of the Related Art
A liquid electrographic imaging system prints a desired image by developing a latent electrostatic image formed on a photosensitive medium such as a photosensitive belt, by using a developing solution, which is a mixture of a volatile liquid carrier and toner, and transfers the developed image onto paper.
FIG. 1 schematically shows the structure of a conventional liquid electrographic color imaging system. Referring to the drawing, a photosensitive belt 110 operates by being supported by a plurality of rollers 121, 122 and 123. Electrostatic charges remaining on the photosensitive belt 110 are removed by an erasure station 170 and the surface of the photosensitive belt 110 is charged by a charging station 150 to a constant electric potential. Next, an electrostatic latent image is formed on the photosensitive belt 110 as laser scanning units 130 emit laser beams according to image signals. The formed electrostatic latent image is developed by a developing station 140 which supplies a developing solution containing toner. As shown in the drawing, a plurality of laser scanning units 130 and developing stations 140 are equipped to handle a multitude of colors for a color imaging system.
The developing station 140, as shown in FIG. 2, includes a developer roller 141, a cleaning roller 142 and squeegee rollers 144 and 146 which are installed under the photosensitive belt 110, and a developing solution 148 which is a mixture of toner having a predetermined color, and a liquid carrier. Reference numeral 143 represents a developing solution supplier for supplying the developing solution 148 between the developing roller 141 and the photosensitive belt 110.
The squeegee rollers 144 and 146 remove the liquid carrier among a developing solution 148L attached to the electrostatic latent image of the photosensitive belt 110 and the removed liquid carrier is collected in the developing station 140 by blades 145 and 147.
The developing solution 148L attached to the photosensitive belt 110 according to the electrostatic latent image is evaporated as it passes through an image drying station 160, to thereby leave evaporated toner 148D only.
Next, when the photosensitive belt 110 passes between the roller 121 (see FIG. 1) and the transfer roller 124, the image formed by the toner 148D attached to the photosensitive belt 110 is transferred via the transfer roller 124 to a paper 126 supplied between the transfer roller 124 and a fixation roller 125, so that the image is finally printed.
However, although the printing of an image to the paper 126 is complete, a small amount of toner remains on the transfer roller 124. Also, foreign materials such as dust brought into the inside of the imaging system may stick to the transfer roller 124. Such remaining toner or foreign material contribute to lowering the print quality through repeated print processes.